Treatment of ores



June 10 1924.

J. H.. HIRT TREATMENT OF ORES Filed Feb 2., 1920 'Patented `inne 10, 1924;

JULFS EECTOR EIRT, OF EL PASO, TEXAS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO'

MEXICAN NORTHERN MINING AND RAILWAY COMPANY, A CORPORATION' OF DELAWABE.

rmrmnxr or'oars.,

Applicationfiled February 2, 1929. Serial No. 355,681.

To all whom it may concem:

Be known that I, JULEs Hnoroi HIRT, a citizen of the United El Paso, in the county of El Paso,State of Texas, have invented certain new and useful Improvements in the Treatment of Ores; and I do hereby declare the following to be a, full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains' to 'make and use the same.

This invention relates to an improved process of chloridizing ores, concentrates, and other metallurgical products, to convert the metal values into chlorides or ox chlorides, which are retained in the ore bo y and recovered therefrom, ;for example, by'

leaching with a, suitable solvent. It is' a characteristic advantage of the invention that the chloridizing operation is accomplished without objectionable loss of metal values by volatilization.

Ih the chloridizing of ores, it' has been proposed to mix carbonaceous material chloride, and to bring about the heating of the ore by combustionof the admixed fuel. This method, however, that `overheating is diflicult to avoid, owing `.to the high temperature of ignition and combustion of the fuel; and 'it is diificult to prevent loss of chlorides by volatilization when the process is carried out in this way. It is also difficult to ence of excess oxygen and oxidizing 'conditions during the chloridizing operation.

I havediscovered that the objections to such 'prior proposals can be avoided, and that the ore or other .material can be thoroughly chloridized without any objectionab1e`1oss of chlorides by volatilization if hot products of fuel combustion, free from excess air, are caused to pass through a' body or column of the ore mixed with salt or other chloridizing agent. I have fur therdiscovered that a relatively low temperature' of heating the ore by this method will suffice 'for thorough chloridizing, much lower than where the fuel is mixed 'directly with the ore and burned to supply the heat for the chloridizing. ,The process of the present invention accordingly avoids the high 'temperatures resulting from direct States, residing at.

* low about 7 00 with the ore and sodium chloride or other has the objection.

avoid the prs-.

combustion in the ore body or in contact therewith, and effects the chloridizing by means of gaseous products of combustion, free from excess oxygen, which, while still hot, are passed' into the ore body admixed with the` chloridizing agent. This procedure enables the temperature of the ore column undergoing chloridizing, to be closely regulated, and a much better temperature control Secured than is possible where the fuel is mixed directly with the ore and blast roasted.

When the tfuel is mixed with the ore, it is difiicult to maintain a C. since the ignition temperature of the fuel under practical conditions is over 600 C. and the co-mbustion of the fuel in contact with the ore subjects the ore directly to the flame temperature. According to the present invention, a combustible fuel, such as oil or gas, is burned outside the furnace chamber containing the admixed ore and chloridizing agent, and the products of combustion, ,free

ores for the reason that the metallicchlo- `rides of old, silver; copper, lead, etc., are

volatilize at temperatures much below the ignition temperatures of ordinary fuel combustion. 'For instance, silver chloride begins to Volatilize at about 450 C. gold chloride atabout l50 E'. etc., and these or somewhat higher temperatures will suflice for the chloridizing operation.

In the presence of combustion products free, or practically free from oxygen, this tendency of the chlorides to volatilize is ,reduced to a minimum, while it is nevertheless possible to raise'the heating temperature to` such a point as to efl ect rapid' chloridizing, e. g., to or somewhat above' the meltin the chlori e.

It is a^characteristic advantage of the process of the present invention that the ore does not require fine crushing, that it is thoroughly dried before entering the reaction zone even when it contains consideror volatilization temperature of able moisture, and that it is subjected to a chloridizin action which insures rapid and` thorough c loridizing; while the temperature of the ore column is under the ready control of the operator. Among other advantages of the nvention are the high fuel eliciency obtainable, due to the fact that the products of combustion are passed directly through the ore column so that the exit gases are practically cold,-the heat of the gases being used first for electing the chloridizing and thereafter tor preheating the incoming fresh charge.

The, present invention, as above noted, is of special value in the chloridizing of copper, lead, silver and gold ores, for the production of the corresponding chlorides without loss thereof by volatilization, 'even where the chlorides volatilize at relatively low temperatures. As a result of the chloridizingoperation, the metal values are converted into chlorides or oXy-chlorides, which -are retained in the ore body discharged from the furnace, and subscquently recovered therefrom by leaching. The ores are referably oxide or oxidized ore., but. sulfi e ores may also be treated.

The improved process of the present in- Vention can be carried out in difl'erent types of apparatus, provided the ore body is subjected to products of combstion which are free from excessoxygen, and which are at a sufficient temperature to insure the chloridizing action, 'when the ore is subjected to the chloridizing action of a common salt or other chloridizing agent,

A. furnace adapted for use in carrying i out the method as illustrated in the accompanying drawing in which lFigure 1 is a vertical section through the furnace and lFigure 2 is the section on the line 2-2 of Figure 1.

A particularly advantageous manner of carrying' out the improved process is to feed the ore 5 progressively down through an upright furnace 6 somewhat similar to a lime kiln and to supply the products of combustion to the mixture of ore and chloride near the central part 7 of the furnace. The central part of the furnace may thus be surrounded by a combustion chamber opening into the 'urnace through a series of openings; or the vertical fur-Ilace, if 'rectangular in section', may have combustion chambers 8 in its side walls and lateral openings 9 therefrom into the furnace chamber containing the charge. Fuel and ore may be introduced through the burners 10. The upright or vertical retort or furnace chamber should preferably have a sufiicient height so that the products of combustion will be completely cooled in their upward passage through the incoming charge and so that they Will give up their heat to the incoming charge. So also, the reduction in temperaeter@ ture of the escaping products of combustion assists in preventing any tendency toward escape of the .volatile chlorides which are condensed in the cooler portions of the incoming charge and returned to the chloridizing zone. Any excess volatile metal chloride will thus be caused to pass downwardly where it will condense in the cooler portions of the chloridized material prior to its escape from the bottom of the-urnace chamber. Tt will be understood that the 'urnace or retort will be constructed ot suitable material resistant to the Chemical action of the materials undergoing reaction therein. I

lln order to provide for proper cooling ot the chloridized material in its passage downwardly through the lower portions of the urnace chamber or retort, such lower portions should be provided with cooling means or should be so exposed that the desired cooling will take place so that the outgoing body of chloridized ore will be discharged at a relatively low temperature, well below that of condensation of any ot the 'volatile chlorides.

With the vertical furnace of the character above referred to, the procws can be made continuous by charging the ore together With sodium chloride or other chloridizing agent at the top and regulating the discharge of the eooled chloridized ore at the bottom. The ore itself, both before and after chloridizing, Will 'form an efi'ective seal' for the furnace cha-mber or retort and the cooler portions of the incoming and outgoing ore bodies will condense any chloride or oxychloride vapors that would otherwise tend to escape therefrom.

llt is a characteristic feature and advantage of the improved process .of the present invention that the body of ore requires maximum heating only at or near the temperature offormation of the chlorides, and that the furnace need be heated tor only a portion`of its length. That is, the ore body need not be maintained for a prolonged period of time at an elevated temperature in the chloridizing zone.,

llt is a further advantage of the invention, as above mentioned, that very low temperatures are sufficient therefona with resulting marked economy in the heat required and reduction of the corrosive action upon the retort or furnace.

lt crude oil or tuel is used to supply the products of combustion such oil may be burned in the combustion chamber with avoidance of eXcess air and the resulting products of combustion then passed directly into the ore body so that the ore body admiXed with the sodium chloride or other chloride, will be subjected to the direct heating action of the products of combustion. While a small amount of excess oxygen may cess should be avoided.

eaders' be tolerated in the process without objec tionable volatilization, any considerable eX- Higher temperatures, such as those of the flame itself, should likewise be avoided. v

The amount of sodium chloride or other chloridizing agent required to be admixed with the ore will vary with the .amount of the metal values tobe chloridized. It is not necessary to use a .large excess of the chloridizing agent, and, for silver, gold and low grade copper ores, as little at 1 or 2%, or even 'less may suflice, although a larger amount can be used.

It is an advantage of the present process that fine grinding of the ore is not necessary, but relatively large lumps of ore can'beused provided they are' sufliciently porous.

Although the temperature at which sodium chloride will melt and volatilize is a relatively high temperature, nevertheless temperature,

efiective chloridizing can be etfected with sodium chloride, according to the process of the present invention, at a much lower inasmuch as the sodium chloride will react with sulfur dioxide or moisture present in small amount in the' products of combustion. For example, where crude oil is used as the fuel for producing the products of combustion, the products of combu'stion will contain appreciable amounts of steam in a highly reactive form. So also, where the crude oil contains appreciable amounts of sulfur, this will be oxidized and the resulting sulfur dioxide or sulfur trioxide will be present in small amount in the productsof combustion and will contribute to the chloridizing process..

Where increased amounts of reactive steam or sulfur doxde are desrable, these can be supplied by adding further amounts of' steam in admixture with the products of combustion and by adding small amounts of sulfur, for example, by suspending it in a finely-divided state in the fuel oil.

In a vertical shaft furnace, such asabove described, having a furnace chamber adjacent the ore surrounding its central portions for supplying the products of combustion to the shaft .at an intermediate point of its' height, the effective reacting zone will be at or near the place where the gases are ntroduced. In the continuous operation of such a furnace, the heated chloridized ore will retain its heat for an appreciable time as it passes downwardly from the chloridizing zone and a further opportunity will thus be permitted in 'the completion of the chloridizing. The main chloridizing actin, however, will take place where the products of combustion enter the shaft or somewhat thereabout inasmuch as the hot gases tend to rise in the shaft and to impart their heat to the incoming charge as it progresses slowly down toward the V containing a small percentage or even a.

fraction of a per-cent of metal sulfides, 'it .may be of advantage to introduce a small amount of oxy en with the products of combustion to a ist in the oxidation of the sulfur, but, as above pointed out, any such amount 'of excess oxygen as would give oxidizng conditions and cause appreciable loss by volatilization should be avoided.

Instead of carrying out the process in furnacs. constructed as above described,

i other suitable types of furnaces can be used w'hich willenable the desired heating to be brought about by means of products of combustion in the manner above described.

After the ore has been chloridized and the metal values converted into chlorides or DXy-chlorides, the ore is then subjected-to a leaching operation for -the purpose of eX- .tracting therefrom the chlorides or oxychlorides so formed. In this leaching operation any suitable solvent can be used which will dissolve the chlorides formed. The ore may thus be leached with a Cyanide solvent, with a hyposulfite solution, with a saturated brine (sodium chloride) solution, with an acid brine solution (containing 1 or 2% of -hydrochloric or sulfuric acid), a brine solution containing ferric chloride, etc. The ore may thus be leached inany suitable manner which is available for the leaching and extraction of the chloridizedvalues; and'the values 'can be recovered from the leach liquid thus produced in any suitable manner, as will be readilyunderstood.

Having thus'described my invention, what I claim isz i 1. The method of chloridi'zing'ores, metallurgica'l products and the like, which com-.

prses'subjecting a compact body of the same admixed with a suitab e` chloride 'to the direct heatin action of products of combustion free rom any appreciable excess of prises progressing a charge of the ore adniXed with a chloridizing &gent downW-ardly through a Vertical shaft furnace or retort and heating the' same by the introduction of products of conbustion free froni any appreciable excess of oxygen into the clarge at an intermediate point, escape of volatile chlorides With' the escaping products of conibustion being prevented; substantially zs'de- Scribed.

4. The method of chloridizing ores, netallurgica] products and' the like, which comprises progre'ssively :feeding a charge of the material to be chloridized through a preh'eating zone, a chloridizing zone, and a cooling -zone, and subjecting the material to the action of thechlordizing agent in the chloridizing zone While heating the material by the introduction of hot products of combustion, any objectionable escape of vol-atile chlorides being prevented; substantially :is described.

5. The method of chloridizing ores, metallurgical products and the like, which coniprises heating a nixture of the material to be chloridized and sodiun chloride by introducing hot products of conbustion thereto, the products of conbustion being substantially free froni oxygen and containing constituents reacting 'with the sodiun mocem clloride to promote the chloridizing action; v

*metallurgcal material having a chloridizing &gent admixed therewith and thereby forming chlorides of the desired metal values.

7. The method of 'chloridizing which comprises introducing products of conbustion fornied externally thereof, to a compact body of ore or like metallurgical material having a chloridizing agent admixed there- With, thereby forming chlordes of the desired metal values and collecting Volatilized chlorides in overlying layers of said material.

8. The method of chloridizing which coniprises introducing products of combustion fol-med externally thereof and free froni excess oxygen to a body of ore or like metallurgical material having u-chloridizing agent admixed therewith While the body is traveling through a reaction zone and thereby forming chlorides of' the desir'ed metal values.

Tn testinony Whereof T affix my signature.

- JULES HECTOR HTRT. 

